Non-severe hypoglycemia worsens cognitive function in type 2 diabetes

Denmark: Acute non-severe hypoglycaemia (mean plasma glucose 3.1 mmol/l) negatively impacts cognitive function in people with type 2 diabetes (T2D), according to a recent study published in the journal Diabetologia.

Previous studies have demonstrated a relationship between cognitive impairment and hypoglycaemia (<3 mmol/l). Malin Nilsson, Bispebjerg University Hospital, Copenhagen, Denmark, and colleagues in this study hypothesised that non-severe insulin-induced hypoglycaemia reduces cognitive function in individuals with type 2 diabetes.

This randomised crossover study involved 25 patients with type 2 diabetes who attended two experimental visits with hyperinsulinaemic glucose clamping: one hypoglycaemic clamp (plasma glucose 3.0 ± 0.2 mmol/l) and one euglycaemic clamp (plasma glucose 6.0 ± 0.2 mmol/l).

Participants were deemed eligible if their diabetes was treated with diet or glucose-lowering medications (except sulfonylureas or insulin), age was 35-70 years, BMI was 23-35 kg/m2 and HbA1c was below 75 mmol/mol (9%). cognitive function was assessed with a neurocognitive test battery measuring verbal memory, executive function, sustained attention and psychomotor speed.

A measurement for psychomotor speed was selected as the primary outcome. Participants and people assessing the outcomes were blinded to group assignment.

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Key findings include:

• Cognitive performance was impaired during hypoglycaemia with a mean score in the primary outcome test, Symbol Digit Modalities Test measuring psychomotor speed, of 48.7 ± 9.8 (hypoglycaemia) vs 56.6 ± 12.0 (euglycaemia); i.e. a change of -7.9 points.


• In addition, hypoglycaemia reduced the global cognitive score by -0.7.


• A stable glucose plateau was achieved during both experimental visits.


• For the hypoglycaemic clamp, mean plasma glucose concentration (± SD) during neurocognitive testing was 3.1 (± 0.3) mmol/l.


• Age, sex, fasting C-peptide, counter-regulatory hormones and the severity of hypoglycaemic symptoms did not influence cognitive function.

Also Read: Intensive blood sugar lowering therapy makes 20 percent diabetics vulnerable to hypoglycemia

"Acute non-severe hypoglycaemia (mean plasma glucose 3.1 mmol/l) has a substantial negative impact on cognitive function in individuals with type 2 diabetes," concluded the authors.

More information: Experimental non-severe hypoglycaemia substantially impairs cognitive function in type 2 diabetes: a randomised crossover trial published in journal Diabetologia.

DOI: https://doi.org/10.1007/s00125-019-4964-4

Journal information: Diabetologia